1. Field of the Invention
The invention relates generally to check valves for preventing the backflow, or reverse flow, of fluid into a supply source. More specifically, the invention relates to a unibody, or unitized check valve body construction, capable of being configured for either single or double check valve operation. Internally mounted check valve subassemblies, each including a base with an aperture, a clapper, and a spring loaded cam arm for engagement with the clapper, provide improved fluid pressure loss characteristics, over the working pressure range of the valve.
In the double check valve configuration, the valve body of the present invention may also be fitted with a pressure actuated relief valve, providing a backflow preventer acceptable for use in the most demanding applications, including toxic fluids.
2. Prior Art
Examples of unitized check valve body construction include U.S. Pat. Nos. 4,232,704 and 4,284,097 issued to Becker, et al. In U.S. Pat. No. 4,054,153, granted to Guyton, a check valve is disclosed using a gravity actuated pivotal clapper, suspended by a clapper hanger provided in the valve body. U.S. Pat. No. 2,706,488, issued to Harrington, shows a multi-sectional back flow preventer, claiming the characteristic of providing a relatively low pressure drop during maximum flow conditions.